Polymorphs of oxotitanium phthalocyanine exhibiting large third-order nonlinear optical susceptibility

Abstract

Metallophthalocyanines have been considered valuable materials for the development of nonlinear optical devices because of their versatility, architectural flexibility, exceptionally high environmental stability, and ease of processing and fabrication. Furthermore physical properties of metallophthalocyanines can be tailored over a wide range either by inclusion of a variety of central metal atoms or by substituting peripheral functionalities at the ring. Phthalocyanine ring has a two-dimensional conjugated π-electron system and the magnitude of third-order nonlinear optical susceptibility χ(3) varies by several orders depending on the metal atom substitution.1-7 Recently polymorphs of oxotitanium phthalocyanine (TiOPc) have been utilized in developing photoreceptor devices8-10 and their photoconductivities were found to vary remarkably depending on the crystal structures. With same view, we selected to investigate the third-order nonlinear optical properties of different polymorphs of TiOPc. This report discusses a systematic study of the third-order nonlinear optical properties of amorphous, α, β, and Y polymorphs of oxotitanium phthalocyanine.